1. Field of the Invention
This invention relates to a distribution network monitoring and control system for monitoring and controlling the system status of a distribution network system.
2. Description of the Background
A Distribution Management System (DMS) and distribution network equipments for judging a fault generated in a distribution network system are classified into a Current Sensing System (CSS) and a Voltage Sensing System (VSS).
CSS is a system which is used widely in Europe and America. CSS judges a fault section based on the action of an Over Current Relay (OCR) provided in each switch. A switch for CSS is called a CSW. Hereafter, this switch is referred to as a CSW. A CSW is composed of a switch (SW), a terminal unit (FTU) with communication function and OCR function and a battery.
CSS judges a fault section based on the action state of OCR provided in the switch, and executes an isolation of the fault section and recovering operation to the non-faulted section.
VSS is a system which is used widely in Japan. VSS judges a fault section by a Fault Detecting Relay (FDR) provided in each switch. A switch for VSS is called a VSW. Hereafter, this switch is referred to as a VSW. A VSW is composed of a switch (SW) and a terminal unit (FTU) with communication function and FDR function. A FDR is provided with a function to open a switch automatically when no voltage state is detected, a function to close the switch when voltage is applied, and a function to make locked state when no voltage state is detected within a predetermined time after closing the switch and to keep the opened state even if voltage is applied again. VSS executes isolation of the fault section and recovering operation to the section of power source side from the fault section by a trip, a reclosing, a re-trip and a re-reclosing of a feeder circuit breaker (FCB) and the function of FDR. Then DMS executes a recovering operation to the section of the load side from the fault section.
FIG. 34 shows one example of the construction of a distribution network monitoring and control system having a fault section judging means to judge a fault section when a fault is generated in a distribution line in a CSS type distribution network system which is monitored and controlled using CSWs.
As shown in FIG. 34, a distribution network monitoring and control system 1A is composed of: a monitoring and control means 11 to take in the information of distribution network equipments such as CSWs (hereafter, simply referred to as switches) of a CSS type distribution network system 2 and to output control information for the switches thereof; a status grasping means 12 to judge charging and outage state of CSS type distribution network system 2 according to the information on distribution network equipments taken by monitoring and control means 11; a switch status take-in means 13 to take in the status of the switches in a range to which power was so far transmitted through a feeder causing a fault, as required when the status grasping means 12 judged that a fault was generated; a CSS type fault section judging means 14A to judge a fault section according to the fault information of the switches taken in by switch status take-in means 13; a fault processing means 15 to isolate the fault section detected by CSS type fault section judging means 14A from CSS type distribution network system 2 and to transmit power to an outage section other than the fault section (hereafter, referred to as a recovering operation); and a CSS type recovering procedure preparation means 16A to prepare a recovering operation procedure to the outage section other than the fault section on the assumption that the switches are to be controlled.
Further, switches are provided with batteries and so constructed that they are controllable even in the outage section.
Monitoring and control means 11 receives a distribution network equipment information from CSS type distribution network system 2, and when it is found that the equipment status is changed (hereafter, called as the status change) based on a difference from the information received last time, monitoring and control means 11 notifies status grasping means 12 of the status change content.
Further, monitoring and control means 11 outputs control signals to distribution network equipments composing CSS type distribution network system 2 upon request for control.
Status grasping means 12 judges charging/outage state and fault generation of CSS type distribution network system 2 according to the distribution network equipment information notified from monitoring and control means 11. When it is judged that the fault is generated, status grasping means 12 notifies the generation of the fault to switch status take-in means 13, and after a certain time passed from the generation of the fault, status grasping means 12 requests CSS type fault section judging means 14A to judge the fault section.
Switch status take-in means 13 searches switches in a range to which power was so far transmitted before a fault through the feeder that caused a fault according to the notification from status grasping means 12, requests monitoring and control means 11 to take in the status of the searched switches, and receives the result of the taken-in status through status grasping means 12.
CSS type fault section judging means 14A judges a fault section according to the switch fault information received from status grasping means 12 in response to a fault section judging request from status grasping means 12, and notifies fault processing means 15 of the result.
Fault processing means 15 sends a request for control to isolate the fault section and a request for control to provide a recovering operation to non-faulted outage section to monitoring and control means 11, and receives the controlled result through status grasping means 12.
CSS type recovering procedure preparation means 16A prepares a recovering procedure to non-faulted outage section in response to a request from fault processing means 15, and notifies the result to fault processing means 15.
FIG. 35 is an explanatory diagram for explaining the fault section judging process executed in conventional distribution network monitoring and control system 1A.
In FIG. 35, FIG. 35(a) shows a timing chart of the fault section judging process and FIG. 35(b) shows the construction of a part of CSS type distribution network system 2. In FIG. 35(b), a feeder circuit breaker FCB, switches SW1-SW9 and a tie switch TSW are provided in CSS type distribution network system 2. Furthermore, for each switch, the type of the switch (remote controlled switch or remote controlled switch (tie switch)) is shown with different symbol. Here, it is assumed that a fault is generated in a section between switches SW5 and SW6.
In FIG. 34 and FIG. 35, distribution network monitoring and control system 1A detects an initial breaking of feeder circuit breaker FCB by status grasping means 12, and judges the generation of distribution line fault (FIG. 35(a) at a time {circle around (2)}). When a distribution line fault is generated, relays of switches SW1-SW4 at the power source side from a fault section act, and distribution network monitoring and control system 1A grasps the fault information of switches SW1-SW4 (the relay action state) by the status change notice from switches SW1-SW4 (FIG. 35(a) at times {circle around (1)}, {circle around (3)}, {circle around (5)} and {circle around (7)}).
The relay actions of switches SW1-SW4 may be distinguished for fault factors, such as short circuit, ground circuit, etc. In this case, distribution network monitoring and control system 1A is notified of the information on the relay actions for each factor. Thereafter, the circuit is reclosed by the function of feeder circuit breaker FCB (FIG. 35(a) at a time {circle around (4)}). When a fault continues, feeder circuit breaker FCB is tripped again (FIG. 35(a) at a time {circle around (6)}).
After passing a determined time from the generation of fault (hereafter, called as a time Tdet) (FIG. 35(a) at a time {circle around (8)})), distribution network monitoring and control system 1A executes a forced polling by switch status take-in means 13, receives a fault information of switch SW5 in addition to the fault information of switches SW1-SW4, previously received by the status change notice, takes the status of all the switches in a range to which power was transmitted before the fault through the feeder causing the fault, and grasps the fault information of all the switches that are needed to judge a fault section.
CSS type fault section judging means 14A judges a section between switches SW5-SW6 as a fault section that is a load side section of switch SW5 (hereafter, referred to a fault factor switch) located most close to the load side among the switches which notified the fault information (FIG. 35(a) at a time {circle around (9)}).
Distribution network monitoring and control system 1A isolates a fault section by opening switches SW5-SW6 adjacent to the fault section, and then, by closing a feeder circuit breaker FCB, recovers an outage section at the power source side from the fault section (hereafter, referred to as a power source side non-faulted section) by fault processing means 15. An outage section at a load side from the fault section (hereafter, referred to as a load side non-faulted section) is recovered by preparing a recovering procedure in consideration of the distribution line allowable current of the recovered distribution line by CSS type recovering procedures preparation means 16A.
FIG. 36 shows one example of the construction of a distribution network monitoring and control system 1V having a fault section judging means to judge a fault section when a fault is generated in a distribution line in a VSS type distribution network system 3 which is monitored and controlled using VSWs.
In FIG. 36, the same component elements as those shown in FIG. 34 are assigned with the same reference numerals and a detailed explanation thereof will be omitted.
As shown in FIG. 36, distribution network monitoring and control system 1V is composed of: monitoring and control means 11; status grasping means 12; switch status take-in means 13; a VSS type fault section judging means 14V that searches a switch that is locked for making for no-voltage during the detection time period from the information of taken-in VSWs (hereafter, called simply as switches) and judges the load side of the searched switch as a fault section; fault processing means 15; and a VSS type recovering procedure preparation means 16V to prepare recovering operation procedure to the outage section other than the fault section on the assumption that the switches are to be controlled.
Further, as the switches in the outage section cannot be controlled, it is necessary to control the switches in order from the power source side.
VSS type fault section judging means 14V searches switches in the input lock state from the taken-in information of the switches, judges the load side of the searched switch as a fault section in response to a fault section judging request from status grasping means 12, and notifies fault processing means 15 of the fault section judging result.
VSS type recovering procedure preparation means 16V prepares a recovering procedure to non-faulted outage section in response to a request from fault processing means 15, and notifies the result to fault processing means 15.
In the fault section judging process by the above-mentioned conventional distribution network monitoring and control system 1A, out of CSWs of which the fault information is notified, a load side section of switch SW5 located most close to the load side is judged to be a fault section. However, when the status of a load side switch of the judged fault section could not be taken, that switch might possibly detect fault information, and in the case that the fault information was detected, a fault section may be erroneously judged.
When a self-line loop route, which is a state in which the number of feeders that supply power to a loop circuit is one, is adjacent to the load side of a judged fault section or when a judged fault section is in a self-line loop route, which side becomes a load side section cannot be determined unless the flowing direction of power in the self-line loop route is known. Therefore, a fault section may possibly be judged erroneously.
When a distribution network system before a fault is an other line loop route, which is a state in which the number of feeders which supply power to a loop circuit is two or more, fault information is detected through switches on routes to all feeder circuit breakers FCB from a fault section. In the fault section judging process by the conventional technology, a fault is judged by a feeder circuit breaker FCB that is lastly tripped out of feeder circuit breakers FCB in the other line loop. Then, a load side section of the switch which is most close to the load side from that feeder circuit breaker FCB out of switches of which faults were notified is judged as a fault section, and thus, a fault section may be erroneously judged.
When a plurality of fault factors are generated simultaneously and a plurality of fault factors are on the same route from a tripped feeder circuit breaker FCB, only a load side section of a switch which is most close to the load side is judged to be a fault section, regardless a fault factor, out of switches of which faults are notified according to the fault section judgment of the conventional technology. Accordingly, as the other fault factors are not judged, a fault section may be erroneously judged.
When factors for an intermittent fault, which is a fault that is generated and recovered repeatedly within a short time period, exist in a plurality of sections, only a load side section of a switch which is most close to the load side is judged to be a fault section out of switches of which faults are notified according to the fault section judgment of the conventional technology. Accordingly, as fault factors during the intermediate time cannot be judged, a fault section may be erroneously judged.
When a fault section was erroneously judged as described above, feeder circuit breaker FCB might be tripped in the recovering operation to a non-faulted section at a power source side or in the recovering operation to a non-faulted section at a load side, causing the extension of an outage time and the expansion of an outage section.
Further, in a mixed type distribution network system wherein CSWs and VSWs are provided in mix, there are problems described below.
That is, when there is provided only one function of either a VSS type fault processing system or a CSS type fault processing system, a fault section may not be detected depending on a system status when a fault is generated.
Also, when only an recovering procedure preparation system that is the same system as that of a fault section judging system is selectable, a recovering procedure may not be prepared.
In addition, when a fault is judged as an intermittent fault, a fault section cannot be judged by a VSS type fault processing system but the whole sections are judged as fault sections. Thus, the fault section judgment may not be made in a pre-selected fault processing system.
Further, according to the fault section judging result by either a VSS type fault processing system or a CSS type fault processing system, fault sections may not be limited sufficiently.
Furthermore, in the case of a VSS type fault processing system, reclosing is indispensable. Accordingly, even in the case that a fault section can be judged according to a CSS type fault processing system, because feeder circuit breaker FCB is reclosed for a VSS type fault processing system, feeder circuit breaker FCB is tripped again, and an outage time of non-faulted section at the power source side becomes long.